1. Field of the Invention
This invention relates in a first aspect to an abrasive tool for grinding or polishing, comprising a grippable shaft having an end flange, an abrasive disc having a fixing flange, and an elastomeric pad, which is disposed between and vulcanization-bonded to said flanges.
In another aspect the invention relates to an abrasive tool for grinding or polishing, comprising a grippable shaft formed with external screw threads and provided with an end flange, a sleeve, and an annular elastomeric pad which is disposed between and vulcanization-bonded to said shaft and to said sleeve.
2. Description of the Prior Art
U.S. Pat. No. 2,629,990 discloses a grinding disc, which is provided with a grippable shaft having an end flange, which is connected by a vulcanization-bonded elastomeric pad to a fixing flange of the grinding disc. That design has been adopted to ensure a resilient contact between the disc and the workpiece.
Published German Application No. 33 01 210 discloses a carrying head for machining discs, which head comprises a grippable shaft and an end flange. The grippable shaft is provided with screw threads and is vulcanization-bonded to an elastomeric pad, which is surrounded by a sleeve. That proposal is concerned with the provision of a movable carrying head which can yield without a jerk.
Published German Application No. 32 22 858 relates to a grinding or polishing tool comprising an abrasive disc, which is provided with a grinding or polishing abrasive and which by means of an end piece of a flexible shaft is adapted to be connected to a driving chuck. The flexible shaft is adapted to be stiffened by means of a rigid member which is adapted to be inserted into or fitted on said shaft.
It has thus been disclosed that a grinding disc can be driven by means of a flexible shaft, which can be stiffened by a rigid member that is inserted into or fitted on the shaft so that one and the same apparatus can be used for grinding and polishing flat surfaces when the shaft has been stiffened. In the use of such discs it has been found that the flexible shafts may break under excessive stresses when they are operated under heavy loads, which may be due to the size of the grinding disc or to high speeds, which in angle grinders may amount to about 9000 r.p.m. whereas only speeds of about 3000 r.p.m. are required in drilling or boring machines.